1 files changed, 3 insertions, 0 deletions

diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c
index 265983635f2b..3647c65a0f48 100644
--- a/fs/fat/fatent.c
+++ b/fs/fat/fatent.c
@@ -388,8 +388,11 @@ static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs,
                                 err = -ENOMEM;
                                 goto error;
                         }
+                        /* Avoid race with userspace read via bdev */
+                        lock_buffer(c_bh);
                         memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
                         set_buffer_uptodate(c_bh);
+                        unlock_buffer(c_bh);
                         mark_buffer_dirty_inode(c_bh, sbi->fat_inode);
                         if (sb->s_flags & SB_SYNCHRONOUS)
                                 err = sync_dirty_buffer(c_bh);